27 September 2011

Question Place

I'm now back from my hiatus from the net, and will be putting up pictures and science comments on them over the next few days/weeks.

But first, here's a place and chance to ask questions and make suggestions.  I've been pretty thoroughly off-net since the 8th, so please be sure to provide links if you're asking about recent events.  (See the link policy; links to science content are good things whether I've been off-net or not.)


Liz said...

Since your blog runs the gamut so nicely ... how about a history lesson for my middle schoolers? They respond with the equivalent of "no DUH" when presented with information about global warming, yet there's much rhetoric in the media about how global warming isn't actually happening and those who say it is are the equivalent of scientific cockroaches. Perhaps you could either provide some useful links or a brief history lesson for us. Thanks.

Hank Roberts said...

Liz, may I suggest this history lesson? I'm sure your kids are smart enough to make the connection:

http://ajph.aphapublications.org/cgi/reprint/90/1/36 (pdf)

Anonymous said...


I hope this is the place to ask this!

A denier tells me that AGW is not 'falsifiable' -using Karl Popper's criterion. He sounds right from a rigid understanding of that term. Is it and how do I thwart his evil argument?



Robert Grumbine said...

Sorry Robert, My first try to respond, a couple of days ago, apparently got swallowed by blogger.

Fingers crossed:
A full post will follow (shortly?). But for now:
'evil' is something I'd leave aside, not really helpful.

In response to your discussant (I also suggest here avoiding terms like 'denier'), I'd suggest a couple of things.

first: ask him to define what he means by 'AGW'. You both probably think you know what you each mean, but chances are good you don't mean the same thing. The thing you have in mind could be in perfect agreement with Popper, while the thing that he has in mind is entirely inconsistent with it.

Second, the bad news, maybe, is that Popper is not really the be-all end-all of defining science. While scientists tend to like his definition, there are some real problems with Popper's approach if you look in to the fuzzier areas (not least, it denies the existence of fuzziness).

Climate isn't really a fuzzy area with respect to Popper, at least not with some reasonable care in defining what you're talking about (hence the first suggestion).

So let's take up 'AGW' as meaning Anthropogenic Global Warming. One part of this is obviously, and in a logical sense, easily, falsifiable -- 'Global Warming'. If the globe has not warmed, then there can't be an AGW.

Next, turn to the 'Anthropogenic'. Could it be falsified that some of the observed warming is due to human activities? Sure. The attribution to human activity relies on a few different points (observations, at this point of the science):
1) There is a greenhouse effect on the earth
2) CO2, CH4, and some other gases are greenhouse gases
3) The levels of those gases have risen
4) The reason is human activity
5) Global mean temperature is sensitive enough to #2 + #3 to change observably.
6) Global mean temperature has indeed warmed
7) There are no other good candidates for the magnitude and timing of the warming.

Each of those 7 could be falsified, so Popper's criterion is happy. It could be that humans didn't release greenhouse gases, or if they did that the amounts were negligible, or if they weren't then climate wasn't sensitive enough to the amounts to matter, and so on. At various times, folks like the person you're talking to have claimed exactly that.

Ironically, the full range of their 'denial' points to exactly how it is that AGW (as I've taken it here) is indeed falsifiable in Popper's sense.

jacob l said...

I know this is a weather question
but I have noticed a "dry layer"
during inversions, as an example over Spokane,Washington http://weather.uwyo.edu/cgi-bin/sounding?region=naconf&TYPE=TEXT%3ALIST&YEAR=2011&MONTH=12&FROM=0812&TO=0812&STNM=72786,
is this "dry layer" real?, if so why
thank you jacob l

Hank Roberts said...

http://www.skepticalscience.com/pics/MSU_cherries.gif might be a nice illustration for your discussion of results on deciding trends; it's from http://www.skepticalscience.com/news.php?p=3&t=130&&n=1005

Also a re-recommendation of the very cool slider graph tool here -- page down to get to it:

(there was supposed to be another version of that coming along sometime; I haven't seen it)

Robert Grumbine said...


I'm sorry about taking so long, but I'm afraid that even so, I don't have much to say. Too much of a weather question for me to engage with very well. Relative humidities of ~20%, such as occur in that sounding around 850-720 hPa, aren't unheard of. Spokane, Washington is also well away from the ocean, and notoriously dry (a friend lives in that part of the state). So moister air near the ground (evaporation from the ground), dry air in the middle layers (winds perhaps from the east, where it's even drier and farther from the ocean), and moister in the mid-troposphere (500 hPa, fed by the prevailing westerlies off the ocean and uninterrupted by the Cascades) seem plausible to me.

But weather sounding interpretation by an oceanographer is likely not the best route. Do we have a meteorologist in the audience?